The invention relates to a medical intromission kit comprising an inner sleeve of flexible material, of which the distal end portion tapers slightly conically in the distal direction while its inside diameter remains the same, and coaxial therewith an outer sleeve of flexible material, of which the proximal end portion includes a seal which allows passage of at least the inner sleeve and occluding completely the inner lumen of the outer sleeve when the inner sleeve is withdrawn, the inner sleeve and the outer sleeve being adapted for axial displacement in respect of each other.
Such an intromission kit is described in U.S. Pat. No. 4,430,081. In most cases, placing of the intromission kit is effected by the so-called Seldinger technique, in which initially for example the artery is punctured with a metal cannula through which a flexible guide wire is pushed into the vascular lumen. Afterwards, the metal cannula is withdrawn. The intromission kit consisting of an inner sleeve and enclosing this an outer sleeve, is then pushed onto the guide wire. At this stage, firstly the end portion of the inner sleeve which tapers conically towards the distal end is introduced into the vascular lumen through the aperture formed by the metal cannula and is pushed sufficiently far forwards, widening out this aperture, for the outer sleeve to be disposed sufficiently far into the vessel.
The inner lumen of the outer sleeve is at the proximal end portion sealed by a packing constituted, for example, by a stellate or round rubber lip, these being disposed one behind the other and fitting closely around the inner sleeve so that no blood can emerge from the artery even when the inner sleeve and the guide wire are withdrawn from the outer sleeve.
The outer sleeve with the proximal seal is also referred to as a plastic sluice. A properly placed sluice can make it possible to pass through quickly and without problem various catheters, endoscopes or other instruments such as, for example, biopsy forceps, without the puncture site being damaged every time there is a change.
Pushed onto the inner sleeve, the outer sleeve forms an annular outer shoulder in relation to the outside diameter of the inner sleeve and by reason of the thin wall thickness of the outer sleeve, upon passage through the vascular opening, causes a slipping-on and piercing of the distal end portion of the outer sleeve and consequently vascular wall lesions or extensive damage to the tissue along the puncture channel in the case of a puncture into parenchymatous organs, unless this damage is recognised at once. It is by no means rare for such damage to cause the emergence of blood if the sluice is recumbent or to secondary bleeding and in isolated cases, in the case of vascular punctures, it may even produce scar-like structures if the vascular lumen becomes torn.
The size of the outside diameter of the outer sleeve is limited by the fact that upon removal of the sluice, closure of the percutaneous puncture aperture should close without any operative procedure, for example in the case of an artery, by compression of approx. 30 to 60 minutes. With increasing outside diameter, furthermore, the wall thickness of the outer sleeve increases, i.e. the step in the intromission direction and thus the above-described risk will be entailed.